Web site design and developement

I would like a directory style website to allow my clients a one page portal to advertise their business. It would need to be searchable by town as well as post code and I would like it to have a simple registration form and posisbly a booking form too. there would be no need to take cash payments on the site at the moment but it would be important that the site could be added to with addistional functionality later. The site should be designed in such a way that the individual businesses can update their own pages. These would be based on a series of temlates.